Non-oriented electrical steel sheets used for iron cores of motors and the like are subjected to forming processes including shearing, such as shear cutting and punching, for increasing productivity. In this case, plastic strain and elastic strain are introduced to the steel sheets during shearing, causing an increase in iron loss.
In particular, in the case of core size being small and the steel sheet having a small width after subjection to shearing, deterioration of iron loss properties due to strain is quite conspicuous and the actual iron loss results are greatly different from those obtained with an evaluation method prescribed in a JIS standard, which fact causes a problem of not being able to obtain motor properties as designed.
In general, to predict motor properties with high accuracy at the design stage, it is necessary in the analysis of electromagnetic field and the like to use iron loss properties that take into account the influence of shearing. As such a method for simulating iron loss properties taking into consideration the influence of shearing, for example, DENSO Technical Review, vol. 12, No. 2, 2007, pp. 129-135 (NPL 1) describes a technique of actually measuring the iron loss after shearing and incorporating the measurements into the simulation, and Journal of the Institute of Electrical Engineers of Japan, Vol. 131, No. 7, 2011, pp. 567-574 (NPL 2) describes a technique of predicting the iron loss of a single plate under tensile and compressive stress in combination with the amount of strain determined by elasto-plastic deformation analysis.